Rather, markets are once again feeling antsy about the Iberian nation's banking problems as macroeconomic conditions start to deteriorate.

"The UK referendum hit an already vulnerable banking system in the eurozone. Italian banks are on the front burner, but the temperature is rising in Portugal," Marc Chandler, the global head of currency strategy at Brown Brothers Harriman, wrote in a Monday note to clients.

"The country is struggling with a systemic banking crisis, the lack of a convincing medium-term fiscal plan and excessive public and private sector leverage," a Barclays team led by Antonio Garcia Pascual observed in a note to clients.

"This brings into question whether Portugal can address all of these issues without the help of another programme."

Nonperforming loans are high in Portugal.
Barclays
Regarding Portugal's financial system, its banks are loaded with bad debts and are starved for capital.

"The Portuguese banking system continues to operate in a challenging environment," the International Monetary Fund wrote in a June 30 report.

"Banks remain liquid, but weak asset quality, low interest margins, and sluggish lending growth remain a drag on their profitability. The process of balance sheet repair has moved slowly, with a large share of banking assets still tied up in low-productivity firms, thereby constraining economic activity."

Portugal's largest deposit taker, Caixa Geral de Depositos, needs a cash injection of 5 billion euros ($5.53 billion), while its largest private bank, BCP, is facing similar issues and may need an estimated 2.5 billion euros ($2.76 billion), according to Barclays estimates, which exclude any positive effect the repayment of so-called CoCos could have.

Portugal also has other issues simmering in the background that are unlikely to make things easier:

Public debt is about 130% of gross domestic product, and some analysts think it could remain above that level through 2020. Additionally, private-sector debt is much higher than that of some of Portugal's European peers, which you can see in the chart below.

Barclays thinks Portugal needs a more "realistic" medium-term fiscal plan that is "consistent with solvency." For what it's worth, the IMF recently forecast that Portugal's budget deficit would be about 3% in 2016 — higher than the 2.2% target — if the country doesn't carry out more spending cuts.

The government will have to face difficult choices on fiscal policies and bank recapitalization. Barclays notes that there is a "non-negligible chance that some of [the government's] MPs could oppose some of the fiscal adjustment that the European Commission is demanding."

Barclays
"All of these factors would require a particularly strong policy response to boost confidence," Pascual's team wrote. "However, the financial markets are concerned about the government's ability to meet all of these challenges."

Portugal's economic performance has been less than stellar since the government exited its bailout program in 2014. Even a trio of tailwinds — cheaper oil, accommodative monetary policy, and stronger euro-area growth (including in Spain— its main trade partner) — could not lift Portuguese growth higher than 1.5% in 2015.

Barclays forecasts that growth with fall below 1% in 2016, while a Citi Research team led by Ronit Ghose noted that the negative growth effects from the Brexit were likely to hit periphery countries — i.e. Portugal, Spain, Italy, and Greece — harder.

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